Manufacture of wood pulp



Patented Jan. 11, 1933 UNITE!) STATES PATENT orrlca MAURICE c. 'rArLon'Ann runs 1. wnrrn,

TO THE mvrnrnson ALKALI woaxs, or VIRGINIA 1.10 Drawing. Application filed April 17, 1930,

' cementing the woodfibres togetherincluding wood pulp has hitherto are digested with lignins, resins and carbohydrates.

' The application of chlorine and hypochlorites to the conversion of .wood chips into been proposed but these proposals have not developed into satisfactory commercial processes. We believe this to have been dueto a lack of this ability, just noted with respect to the chlorites, to penetratebetween the fibres of the wood, at least as hitherto applied.

According to our invention, the wood chips an aqueous solution containing a chlorite, sodium chlorite or calcium removed even at ordinary temperaturesand with low concentration of the chlorite, but the operation is promoted by carrying out the digestion at elevated temperatures, and

with concentrations of the chlorite approaching saturation of the treating solution. The digestion ma be carried out at temperatures up to 100 or at higher temperatures under superatmospheric pressure and the treat ing solution may contain, for example, 125 grams per liter of calcium chlorite or its equivalent of sodium chlorite. Thepcriod of digestion required varies with different p woods and with wood in diflerent'conditions; using the concentrationsand temperatures just mentioned, the period of digestion may approximate 16 hours, for example.

The following example will illustrate one application of the invention: 100 parts of poplar chips are chargedto a digester to-. .gether with 15 parts of lime 62 parts of calcium chlorite and 500" parts of water. The chips are subjected to digestion in the resultjected to .digestionmay be of usual size.

.rectly, for example, 1n

or human I ene, mzw Yonx, assmnons INC., on new YORK, 11. Y., A conronnrron mur'acrunn or woon rum Serial No. 445,197. Renewed Kay 19, 1932.

' ing liquor at a temperature approximating 100 C. for a period of about 16 hours. The volume ofthe liquor is maintained by addition of water as necessary. Just before the chlorite content :of the liquor is exhausted, 31 additional parts of calcium chlorite are added. At the end of the digestion period the pulp is drained and subjected to further disintegration in a ballmill.

The pulping'action is promoted by agitation of the wood chips during digestion, by rapid circulation of the treating solution through the wood chips or by mechanical agitation, for example. The treating solution may beacid, neutral or alkaline, but it is usually advantageous to use neutral or alka line treatingsolutions. In any, case, the cellulose itself does not seem to besubjected to any destructlve action. The wood. chips sub- The consumption of chlorite in the pulping operation may be reduced, in the case of resinous woods such as pine and spruce, by appropriate pretreatment example, by treatment with steam lutions of ammonium hydroxide.

The pulp product is, by the treatment with the chlorite solution, bleached at the same time that it is pulped, and may be useddithe manufacture of white paper. The pulp product may, however, be subjected to further bleaching treat ment. Such further bleaching may, with advantage, be efiected by treatment with dilute solutions ofhydrochloric acid, solutions containing about 0.4 grams chlori'c acid for example, or may be effected or with soof the chips, for

per liter of hydroby treatment with solutions of sodium bithe chlorites of themetals of the of wood chips, the im-' comprising the alkali-mtals an& the ar lime-cmh-metals.

' 2. In the pulping of woofi chips, the improvement which comprises digesting the 5 wood chips with an aqueous solution con- Mining 2. salt of chlorous acid.

3. In the pulping of wood chips, the improvement which comprises figesting the wood chips with an aqueous solution contain- 13 ing the chlorite raical.

In testimony whereof we afix our signatures.

MAUREOE (3. T

AYLOR. JAMES; F, W cm. 

